# down counter using 74193 ic

Discussion in 'Digital Circuit Design' started by Judy Ann, Oct 1, 2016.

1. ### Judy Ann Thread Starter New Member

Oct 1, 2016
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guys i need help! please give me an idea or schematic diagram of circ, about down counter using 74193 ic ..

2. ### djsfantasi AAC Fanatic!

Apr 11, 2010
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• Down from what?
• To what?
• Do you know how it starts?
• Will it run once or how will it reset?
• When will it stop?

Judy Ann likes this.
3. ### Judy Ann Thread Starter New Member

Oct 1, 2016
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DOWN FROM 0 TO 9 .. IT WILL RESET AT 0 THEN BACK TO 9...

4. ### MrChips Moderator

Oct 2, 2009
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Can you count from 9 to 0 backwards?

Oct 1, 2016
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6. ### djsfantasi AAC Fanatic!

Apr 11, 2010
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Is this homework? And there were a couple of my questions you did not answer.

7. ### Judy Ann Thread Starter New Member

Oct 1, 2016
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this is an activity, yes i have read the data sheet.. i have tried my idea but the count is 9-7-5-3-1, then back to 9..

circuit must have a continuity sir, it will not run once...

8. ### Alec_t AAC Fanatic!

Sep 17, 2013
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Post the circuit of your idea.
Is the 'activity' a school/college project?

9. ### djsfantasi AAC Fanatic!

Apr 11, 2010
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And how does it start? Just by powering on?

Is the count from 9 to 0 or is it 9-7-5-3-1? Details are important?

Assuming it's the latter sequence, is there something unique about it? Can you describe it to us? How would you represent it in binary?

10. ### Judy Ann Thread Starter New Member

Oct 1, 2016
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this is the schematic.. i need it for college project

11. ### Judy Ann Thread Starter New Member

Oct 1, 2016
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by putting the source on.. the count is from 9-7-5-3-1.. there is nothing unique .. when i turn on the source the clock pulse start then the 7segment just display 9-7-5-3-1 number again and again... 1001 - 0111 - 0101 - 0011 - 0001..

12. ### Alec_t AAC Fanatic!

Sep 17, 2013
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Using the A,B,C,D inputs, what value do you need to load in to reset the counter?

13. ### Judy Ann Thread Starter New Member

Oct 1, 2016
10
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need the 1 NAND 1 value to reset the counter. 0101,0111,1101,1111???

14. ### djsfantasi AAC Fanatic!

Apr 11, 2010
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And may I add, there IS something unique about that sequence. Look at it again, either in decimal or binary...

Apr 5, 2008
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Hello,

Have a good look at the binairy values of the A,B,C and D outputs.
How do they relate to the wanted sequence?
Also what values do you need at the input of the counter to start at 9?

Bertus

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16. ### Judy Ann Thread Starter New Member

Oct 1, 2016
10
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need 1001 value to start at 9.

17. ### Judy Ann Thread Starter New Member

Oct 1, 2016
10
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there is nothing unique , the circuit just display 9-7-5-3-1 values

18. ### Papabravo Expert

Feb 24, 2006
10,021
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I'm going to be a spoil sport and let you off the hook. In the given sequence the least significant digit is always a 1. So tie that input to the display high. What do the remaining digits do? That's right they go {100, 011, 010, 001, 000}. Those values concatenated with a constant, always 1, least significant digit, make up the desired sequence. Preset the counter to 4, aka 100, let it count down to 0, and reset the counter to 4 on the next clock after the counter reaches 0. Recognizing patterns is half the secret to clever logic and state machine design. It has always worked for me.

19. ### Alec_t AAC Fanatic!

Sep 17, 2013
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I'm still puzzled. Do you want to count 9-8-7-6-5-4-3-2-1-0-9-8-7-6-........; or should it be 9-7-5-3-1-0-9-7-5-....... ?

20. ### MrChips Moderator

Oct 2, 2009
12,228
3,282
Seems like the LSB is stuck high.